1. Field of the Invention
The present invention relates to a high stiffness waterproof roof panel pad for a vehicle and a manufacturing method thereof, and more particularly, to a high stiffness waterproof roof panel pad for a vehicle, in which a waterproof reinforcing layer having a PE layer is stacked on both surfaces of a urethane foam pad having excellent sound absorption performance, and the urethane foam pad and the waterproof reinforcing layer are formed integrally by laminating the PE layer, and thus it is possible to provide a waterproof function as well as reinforce stiffness, thereby reducing noise and vibration generated and transferred from the roof panel of the vehicle to an inside of the vehicle and also preventing dew condensation, and a manufacturing method thereof.
2. Discussion of Related Art
Generally, in a vehicle, a sound absorbing pad is installed on a vehicle body panel in order to reduce noise or vibration transferred from an outside of the vehicle to an inside thereof and thus to improve ride comfort. The sound absorbing pad needs a complex solution to improvements in fuel efficiency, noise, vibration and the like through a weight of the vehicle.
Accordingly, Patent Document 1 discloses a sound absorbing material having a multilayered structure in which a horizontally arranged sound absorbing material layer and a vertically arranged sound absorbing material are stacked, and a surface-treated non-woven fabric is attached to an outer surface thereof in order to suppress dust generation and also to increase surface uniformity, and a manufacturing method thereof. Here, since the thin surface-treated non-woven fabric is attached to the outer surface so as to perform a finishing process, it is possible to provide the sound absorbing material which may prevent the dust generation at the surface thereof in advance and also increase the surface uniformity. Further, since the sound absorbing material is manufactured so as to have the multilayered structure in which the horizontally arranged sound absorbing material layer which is a high density layer and the vertically arranged sound absorbing material which is a low density layer are mixedly stacked, a difference in surface density occurs between the layers, and it is possible to reduce a weight and further improve performance of the sound absorbing material by the difference in surface density.
As a conventional pad used in a vehicle body panel of a vehicle, a sound absorbing pad in which PET felt is generally used as a base material has been used widely. However, the sound absorbing pad had the following limitations:
(1) In the case of the sound absorbing pad formed of the PET felt, it had sound absorbing ability, but it was not able to reinforce stiffness of the vehicle body. Therefore, it could not reduce noise due to vibration transferred from the vehicle body to the inside of the vehicle.
(2) Further, in winter when a difference in temperature between the inside of the vehicle and the outside thereof was great, dew condensation was generated at an inner side of the vehicle body panel. If the sound absorbing pad was wet due to the dew condensation, then the sound absorbing effect was deteriorated, and the sound absorbing pad could become separated from the vehicle body panel.